1. Field
This invention relates to apparatuses and methods for the conversion of CO2 and to recovery of carbon solids.
2. Description of the Related Art
CO2 is known as a greenhouse gas and is believed by many to be a contributing factor in the phenomenon known as global warming. Consequently, there have been efforts to reduce the amount of CO2 released to the atmosphere. These efforts typically involve reduction of the emission of CO2 gas through the use of alternative energy sources. There are also efforts to reduce atmospheric CO2 gas through enhancing natural CO2 sinks, such as forests, oceans and soils, and developing methods to artificially sequester CO2 gas.
Artificial sequestration of CO2 involves capturing CO2 and then depositing it in an environment in which it will not enter the atmosphere. For example, CO2 is scrubbed from gas resulting from burning of fossil fuels, typically in large scale, power plants, through separation or absorption. CO2 is then injected into a storage location.
One proposed form of sequestration is direct injection of CO2 into the ocean at a depth wherein the CO2 forms solid clathrate hydrates which ultimately dissolve into the surrounding waters. Geological sequestration of CO2 has been used for some decades, through pumping CO2 into declining oil wells to bring more oil to the surface, into unminable coal fields wherein the gas is absorbed into the coal, and into saline aquifers. CO2 is even pumped into caves and abandoned mines.
These methods require a great deal of energy to generate and maintain the required pressure to deliver the gas, which may negate the beneficial effects of sequestration. Also, there are several safety issues that arise from these methods. Moreover, there is some question whether some methods of sequestration considered at this time might cause detrimental environmental effect. Some methods do not yield a useful by-product and, accordingly, the cost of sequestration might outweigh the benefit.
One of the biggest problems faced with disposal of CO2 is the inability to convert CO2 to another useful compound due to its inherent stability and the restraints of entropy. A solution to this problem is found by dissociating the CO2 into elemental carbon and oxygen.
Carbon has been recently found to exist in many different and useful forms, including certain nano-structures known as “fullerenes” which include single-walled carbon nano-tubes, and buckyballs. Hence, the inventors herein have developed a beneficial method and apparatus described below to mitigate the problem of excess CO2 while creating a useful product, namely, nano-structures of carbon solids.